From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E5A0C433DF for ; Wed, 10 Jun 2020 01:08:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 523DB206C3 for ; Wed, 10 Jun 2020 01:08:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fJTk0h8F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726089AbgFJBIE (ORCPT ); Tue, 9 Jun 2020 21:08:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725988AbgFJBIE (ORCPT ); Tue, 9 Jun 2020 21:08:04 -0400 Received: from mail-qk1-x742.google.com (mail-qk1-x742.google.com [IPv6:2607:f8b0:4864:20::742]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37AC4C05BD1E; Tue, 9 Jun 2020 18:08:03 -0700 (PDT) Received: by mail-qk1-x742.google.com with SMTP id 205so568925qkg.3; Tue, 09 Jun 2020 18:08:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=Vamar1imPGmNvjQrf4Z1noIseKJMzzhcgENPsA5na3U=; b=fJTk0h8FxJJAQwFkQza1lwcNACtdjTFZr6vhcgsFpGKBxxZjCFMDQ6XmpukrefLhN9 KUBaakKsqTHUuuR1YwsgfxpQpmMj93G5eSTIsWDKRWmeSa4lm+G6xB2HIN2blsTuw91E 7iK0gXHiPUChe3Luig3UTJs+4gXDXGDh4oHnJ0SRqcGnUldPL/oU1flFuKB+mbsPGa/X Qh8H0rzRNWxTFedfKVEa/89dvP0Zh6AFbXpYbkscc2tQbxZW9A7px3nXNNdSw3jEBrYP qGViUTUf9nmTXDmkySHu68f60FFzs0/F6ssGRjXzJ0pPiRirdO6KzYi1kFy4/gqg2fvr IuXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Vamar1imPGmNvjQrf4Z1noIseKJMzzhcgENPsA5na3U=; b=ScrMwVGJFKXT2NbY/uxNPn4XQ7F3KBYmOnw0TifKXB0mUbpSmicNQp96BYb1HieCek Sqde6Jcv6AI7h4N+5ZDDZL97j3R7MuV68DvZI9tZpDQCBFuslNnrhE6TEnW9TtC16VNs MZIla7cAPWUojstlBsoVvyushDfql78DzBBfHPJdeJOIlo5ojhNYAHO/7kYaIWZKJrwk mzjLvLXeAVXs5gshW7T4UoLJAxctc6K1e0MsP8cT/cug6e+Iwnb/VG3TkhLbgS7HYIrO kBqqnd1DuJiAWhRvUkalc97EAxyVpyP9NsbdsJA3pFPWGrGheOelaXlmYVRQnCJz2iuL kPIA== X-Gm-Message-State: AOAM5328dlcSZuE/BUyG+x/OYGPCCFa/xbGTXuepnU/pAaoG0qi4zTKN V5LsEFYc9wGjyxF70tA20Q== X-Google-Smtp-Source: ABdhPJxoJ/sHIknqpkWtvAQC8xpLyu6qROAktnCeMs1TtRk3G0EWq6N4jDwOJrrSSBWGqbXcpkBRqw== X-Received: by 2002:ae9:c113:: with SMTP id z19mr676879qki.355.1591751282318; Tue, 09 Jun 2020 18:08:02 -0700 (PDT) Received: from moria.home.lan ([2601:19b:c500:a1:7285:c2ff:fed5:c918]) by smtp.gmail.com with ESMTPSA id m53sm12341695qtb.64.2020.06.09.18.08.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2020 18:08:01 -0700 (PDT) Date: Tue, 9 Jun 2020 21:08:00 -0400 From: Kent Overstreet To: Matthew Wilcox Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, viro@zeniv.linux.org.uk, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 2/2] fs: generic_file_buffered_read() now uses find_get_pages_contig Message-ID: <20200610010800.GA4070152@moria.home.lan> References: <20200610001036.3904844-1-kent.overstreet@gmail.com> <20200610001036.3904844-3-kent.overstreet@gmail.com> <20200610004753.GE19604@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200610004753.GE19604@bombadil.infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jun 09, 2020 at 05:47:53PM -0700, Matthew Wilcox wrote: > On Tue, Jun 09, 2020 at 08:10:36PM -0400, Kent Overstreet wrote: > > @@ -2275,83 +2287,93 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, > > struct iov_iter *iter, ssize_t written) > > { > > struct file *filp = iocb->ki_filp; > > + struct file_ra_state *ra = &filp->f_ra; > > struct address_space *mapping = filp->f_mapping; > > struct inode *inode = mapping->host; > > - struct file_ra_state *ra = &filp->f_ra; > > size_t orig_count = iov_iter_count(iter); > > - pgoff_t last_index; > > - int error = 0; > > + struct page *pages[64]; > > That's 512 bytes which seems like a lot of stack space. Would 16 be > enough to see a significant fraction of the benefit? Ah right, we do call into fs code for readahead from here. I'll switch it to kmalloc the page array if it's more than 16.